Magnetic self-mating fiber optic connector and fiber optic switch sensor

ABSTRACT

A system or method for a magnetic self-aligning coupling device for a fiber optic cable. The device includes a first end coupling comprising a first magnet and a second magnet. Both magnets include a mating surface and an annular ring defining an axial aperture. The aperture receives a distal end of a segment of fiber optic cable in a tight fit. The fiber optic cable has an exterior sleeve and a fiber core. The fiber core of the first segment and the second segment of the fiber optic cable are axially aligned by magnetic force in the first and second apertures to create a continuous fiber optic path. A method for detecting a security breach of a door using the self-aligning couplings is also described.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was developed under Contract No. DE-NA0003525 awarded bythe United States Department of Energy/National Nuclear SecurityAdministration. The Government has certain rights in this invention.

BACKGROUND OF THE INVENTION

The application generally relates to a magnetic connector. Theapplication relates more specifically to a self-aligning magneticconnector for a fiber optic circuit and switch sensor.

Currently a balanced magnetic switch, or BMS, is utilized in a securityalarm system as a means of detecting if a door is open or closed. BMSwas developed over 40 years ago. The BMS uses magnetic reed switchesfixed on, e.g., a door frame, and detects when a permanent magnet fixedto the door move as the door opens. There is a need to effectivelydetect unauthorized door entries in a security alarm system, forapplications including industry, energy, aerospace, and United Statesgovernment facilities. The BMS is installed in nearly every securefacility in the United States.

Because of security limitation of the BMS technology, high securitysites are therefore forced to deploy additional sensor systems toaugment the limitations of systems that use BMS sensors. BMS sensorsfunction well for detecting if the monitored door is opened. However, ifa monitored door is not opened but merely penetrated, the BMS sensor isnot able to detect the penetration.

Alternative intrusion detection systems include Video Analytics todetect door openings. However, Video Analytics may generate nuisancealarms as light levels change. For example, if the lights are switchedon or off, or if the lights flicker, a nuisance alarm may be triggered.If the video camera is located in a dark room and directed at the door,light bleeding in from an adjacent hallway may cause a nuisance alarm.Also, variations in ambient sunlight coming through a window, orautomobile headlights from a passing automobile, may also generate anuisance alarm. The need to provide static ambient light conditions hasimpeded the use of Video Analytics to detect door openings. An InfraredIntrusion Detection System (IRIDS) does not depend on the light level inthe secured environment.

Another existing security alarm system employs a Passive Infrared (PIR)sensor. PIRs are also known to generate excessive nuisance alarms. PIRnuisance alarm sources include hot or cold air influx from heating andair conditioning system, hot air and resulting infrared radiation thatemanates from hot computers; windows heated by direct sunlight. An IRIDSwill not alarm when subjected to these nuisance alarm sources. The IRIDSsensor is not subject to these technical limitations of PIR.

What is needed is a self-aligning magnetic coupling for a fiber opticsensor system and method that utilizes fiber optics to create a circuitfor detecting both open and penetrated doors in a security alarm system.

The disclosure is a system and/or method that satisfies one or more ofthese needs or provides other advantageous features. Other features andadvantages will be made apparent from the present specification. Theteachings disclosed extend to those embodiments that fall within thescope of the claims, regardless of whether they accomplish one or moreof the aforementioned needs.

What is needed is a system and/or method that satisfies one or more ofthese needs or provides other advantageous features. Other features andadvantages will be made apparent from the present specification. Theteachings disclosed extend to those embodiments that fall within thescope of the claims, regardless of whether they accomplish one or moreof the aforementioned needs.

SUMMARY OF THE INVENTION

One embodiment relates to a magnetic self-aligning coupling device for afiber optic cable. The magnetic self-aligning coupling device includes afirst end coupling comprising a first magnet. The first magnet includesa first mating surface and a first annular ring defining an axial firstaperture. The first aperture receives a distal end of a first segment offiber optic cable. The fiber optic cable has an exterior sleeve and afiber core. A second end coupling has a second magnet. The second magnetincludes a second mating surface and a second annular ring defining anaxial second aperture. The second aperture receives a distal end of asecond segment of fiber optic cable extending into the second aperture.The fiber optic cable has an exterior sleeve and a fiber core. The fibercore of the first segment and the second segment of the fiber opticcable are axially aligned in the first and second apertures to create acontinuous fiber optic path.

Another embodiment relates to a fiber optic sensing switch. The fiberoptic sensing switch includes a first module, and a second moduledisposed opposite the first module and separated by an air gap. Each ofthe first module and the second module includes a pair of magneticself-mating fiber optic connectors of opposite polarity. The fiber opticconnectors have a first magnet with a first mating surface and firstannular ring defining an axial first aperture. The first aperturereceives a distal end of a segment of fiber optic cable. The fiber opticcable has an exterior sleeve and a fiber core. Also, a second magnet isincluded with a second mating surface and a second annular ring definingan axial second aperture. The second aperture receives a second distalend of a second segment of fiber optic cable extending into the secondaperture. Each of the first and second connectors is disposed within anannular recess with a distal end of the fiber optic cable segment. Theannular recess has an inner diameter greater than an outer diameter ofthe first or second connector disposed therein to provide a radial gapfor flexible movement to allow engagement with an opposing magnet.

Another embodiment relates to a method for detecting a security breachof a protected element includes generating an optical signal by a fiberoptic interrogator; sending the optical signal from a light source inthe fiber optic interrogator via a fiber optic cable to a fiber opticsensing switch first module; providing within the first module anannular recess having an inner diameter greater than a magneticconnector end; aligning the fiber optic cable with a fiber optic loopvia a magnetic coupling having an annular ring supporting the fiberoptic cable; transmitting the optical signal to a second module inoptical communication with a the fiber optic loop; and returning theoptical signal to a light detector in the fiber optic interrogator.

A number of advantages are provided in the disclosed embodiments, whichincludes a novel security system that utilizes fiber optic continuitysensing.

The disclosed invention uses small, washer shaped, neodymium magnetsattached to the ends of a fiber optic to create a magnetic self-aligningfiber optic connector. The magnets are used to self-align and mate thesending and receiving ends of a fiber optic cable.

Another advantage is provided by placing the connectors in a customdesigned module, so that the self-aligning connectors may be utilized asa fiber optic switch sensor, generally referred to hereinafter as FOSS.The FOSS enables fiber optic connectivity between two moving objects andcan be integrated into applications that were previously not possibledue to geometric uncertainties.

Further advantages include magnetic self-aligning fiber optic connectorsand a FOSS system that may be applied to many barriers such as personneldoors, garage and roll-up doors, safes, vaults, nets and tarps. As partof a security system, the FOSS would be utilized as a switch to detectif the barrier has been moved relative to a stationary surface. Thefiber optic continuity sensor loop would be embedded within the barrierto detect penetration and cutting of the secure barrier.

Alternative exemplary embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The application will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 shows a door arranged with a FOSS installed thereon and a fiberoptic cable circuit connected between the frame and door panel.

FIG. 2 shows end views of a pair of self-aligning magnetic connectorends.

FIG. 3 shows a fiber optic terminal coupled by self-aligning magneticconnectors.

FIG. 4 shows a cross-sectional view of opposing modules withself-aligning magnetic connectors.

FIG. 5 shows a cross-sectional end view taken along the lines 5-5 inFIG. 4 .

DETAILED DESCRIPTION OF THE INVENTION

Before turning to the figures which illustrate the exemplary embodimentsin detail, it should be understood that the application is not limitedto the details or methodology set forth in the following description orillustrated in the figures. It should also be understood that thephraseology and terminology employed herein is for the purpose ofdescription only and should not be regarded as limiting. While doorsecurity monitoring is described below, the disclosed invention may bepracticed with respect to other protected elements, e.g., windows,enclosures, vaults, fences and other means of ingress and egress.

Referring to FIGS. 1 and 2 , a fiber optic security switch, or FOSS 10includes a pair of magnetic self-mating fiber optic connectors 12, 14,applied to a door 16 and door frame 18. For clarity, it should beunderstood that magnet connectors 12, 14 are substantially identicalmagnets distinguishable only by opposite magnetic polarities. Inalternate embodiments, magnets 12, 14 may have differing outer radii oraperture radii, so long as symmetry is used to provide alignment. Fiberoptic connectors 12, 14 may include a protective exterior shell 13 ofmetal or plastic to hold magnets 12, 14 and seal sleeve 30 (FIG. 3 )from liquid penetration.

FOSS 10 has a first module 20 secured to door frame 18, and a secondmodule 22 secured to door 16. When door 16 is in a closed position inframe 18, first module 20 is disposed directly opposite second module 22across the gap 24 between frame 18 and door 16. Each module 20, 22secures a pair of self-mating connectors in place in both the door fameand in the door itself, as described in more detail below. Second module22 has a pair of magnets 12, 14 of opposite polarity connected atopposite ends of a segment of fiber-optic cable 26. In an embodiment,the door segment of cable 26 is arranged in a serpentine conductive pathin door 16. In one embodiment, fiber-optic cable 26 covers most of thesurface area of door 16, and comprises a plurality of continuous,generally parallel segments 25 weaving laterally across the door surfaceand spaced a predetermined distance apart, the spacing determined by theminimum size of an opening that would be considered a security breachthat would allow an intruder to access the monitored area. In analternate embodiment the paths 25 may be arranged in a verticaldirection, or in a random pattern with minimum spacing, rather thanparallel. Fiber-optic cable 26 conducts optical signals between module20 and module 22, through door 16.

Referring next to FIG. 2 , an end view of each of the magneticself-mating fiber optic connectors 12, 14 is shown. Each fiber opticconnector 12, 14 comprises an annular ring with an aperture 28. Aperture28 is sized for receiving a plastic core fiber optic cable 26. Cable 26may be secured within aperture 28 by a bonding material or by a frictionfit. Fiber optic cable 26 includes an exterior sleeve 30 that is bondedto the outer fiber optic cable 26. Sleeve 30 increases the diameter offiber optic cable 26 to fit snugly within aperture 28 of thecorresponding washer-shaped magnet 12, 14. Magnets 12, 14 have agenerally planar mating surface 17 that comes into opposing contact whenplaced in proximity with one another. In an embodiment, magnets may bemade from neodymium, or NdFeB. Similar rare-earth magnets or permanentmagnets may be used in other embodiments.

A pair of magnets 12, 14 having attracting magnetic poles in alignmentcreates a self-mating fiber optic connection. Frame module 20 houses asending end and a receiving end of the connection. The sending end is inoptical communication with a light source 32 of a fiber opticinterrogator 34 (FIG. 1 ). Receiving end is in optical communicationwith the light detector side of the fiber optic interrogator 34.

FIG. 3 shows a section of fiber optic cable 26 fiber optic terminal 15coupled by self-aligning magnetic connectors 12, 14. Sleeve 30 entersfiber optic connectors 12, 14 through exterior shell 13, and connectors12, 14 align separate sections of fiber optic cable 26.

Referring next to FIG. 4 a cross-sectional view of opposing modules withself-aligning magnetic connectors 12, 14 is shown. Magnetic self-matingfiber optic connectors 12, 14 form a continuous loop through fiber opticcable 26, including a FOSS arrangement 10.

Fiber optic cable 26 is secured in each module 20, 22, and is spacedaway from the distal end of cable 26 where magnet 12, 14, respectively,is attached, thus allowing the magnet sufficient space to flex and alignwith the adjacent magnet 14, 12, respectively, of opposite magneticpolarity. Two pairs of magnetic connectors mate with one another forminga continuous fiber optic cable loop. Two pairs of self-aligning fiberoptic magnet connectors are utilized in the FOSS configuration. For adoor 16, fiber optic cable 26 comprises a continuous loop that is routedthrough and embedded inside the door. If the fiber optic cable 26 is cutor otherwise becomes discontinuous, light from the optical signal isprevented from being received at detector 35, and an alarm condition isgenerated by detector 35. The direction of light transmission isindicated by arrows 37. Cable 26 may be routed on an exterior of thedoor 16 in another embodiment.

Due to the self-aligning nature of the magnets 12, 14, as opposing endsof the connection move nearer to one another, the magnetic poles beginto align, and the magnets attract. Therefore, when the connection ispulled apart and magnets 12, 14 are separated, the axially disposedapertures 28 of magnets 12, 14 maintain alignment with each other. Thefiber optic cables 26 fixed within the center aperture of the magnetsare thus forced to point directly at one another. Depending on the typeof fiber optic and interrogator selected, the light signal continues totravel across the connection as magnets 12, 14 of opposing polarity arepulled apart. This phenomena in a controlled fixture allows forintegration into new, previously not possible applications.

Detecting whether a door is open or closed is an exemplary applicationusing the magnetic self-aligning fiber optic connector as a switch, orFOSS. The magnet connectors are used in combination with a breachdetection loop of fiber optic cable 26 routed through the door resultingin a system capable of detecting a position of door 16 relative to doorframe 18, i.e., open or closed, and whether door 16 is being penetratedvia loss of continuity.

Geometric variability exists between door 16 and door frame 18. To usefiber optic continuity as a detection mechanism in a switch, toleranceflexibility must be achieved. To accomplish this flexibility, a methodto implement magnetic self-aligning connectors in a door assembly hasbeen described.

As described above with respect to FIG. 1 , fiber optic interrogator 34transmits a light signal into a length of fiber optic cable 26, and alight detector 35 detects the light signal returning to interrogator 34at the opposite end of cable 26. If the expected light signal isdetected by detector 35, then interrogator 34 is in the “alarm off”state. If the expected light signal is not received by detector 35, theninterrogator 34 switches to an “alarm on” state.

Referring next to FIGS. 4 and 5 , FOSS 10 includes module 20 and module22 positioned opposite one another across a door gap 24. Module 20 hasan embedded fiber optic cable 26 for a transmitted light signalpropagating from light source 34, in a direction indicated bydirectional arrow 37. Cable 26 enters a hollow annular recess 40 inmodule 20. Annular recess 40 has an inner diameter greater than an outerdiameter of magnets 12 or 14. A radial gap 42 between the inner wall ofrecess 40 and outer wall of magnet 12 or 14 provides axial flexibilityfor coupling cable 26. The connecter end of cable 26 at magnet 12, 14 isnot rigidly secured in module 20. Fiber optic cable 26 is secured inmodule 20 a distance from the magnet equal to the length of recess 40,allowing the connector end of the fiber optic and corresponding magnetto move into position and self-align with the magnet on the opposingside of FOSS 10. FIG. 5 shows the arrangement of circular magnets 12, 14within the larger annulus 42 of recess 40, to move axially around 360degrees.

Referring again to FIG. 1 , door 16 is mounted to frame 18 via hinges44. Hinges allowing two pairs of magnetic self-aligning fiber opticconnectors 12, 14 in modules 20, 22, to pass adjacent one other. In thedoor closed position, continuity of fiber optic cable 26 is achieved,and detector 35 reads the input signal from the light source 34. Whenthe two parts of the assembly are rotated, the fiber optic cables 26 areno longer aligned and detector 35 does not receive light, setting off analarm. Depending on the fiber optic interrogator selected andsensitivity required, a gap between the upper and lower portion of theassembly can be varied within about 3.175 millimeters (0.125 inch).

While the exemplary embodiments described herein relate to a doorsecurity monitoring system associated with a door, it is important tonote that the construction and arrangement of the fiber optic switchsensor, as shown in the various exemplary embodiments is illustrativeonly. Although only a few embodiments have been described in detail inthis disclosure, those skilled in the art who review this disclosurewill readily appreciate that many modifications are possible (e.g.,variations in sizes, dimensions, structures, shapes and proportions ofthe various elements, values of parameters, mounting arrangements, useof materials, colors, orientations, etc.) without materially departingfrom the novel teachings and advantages of the subject matter recited inthe claims. For example, elements shown as integrally formed may beconstructed of multiple parts or elements, the position of elements maybe reversed or otherwise varied, and the nature or number of discreteelements or positions may be altered or varied. Accordingly, all suchmodifications are intended to be included within the scope of thepresent application. The order or sequence of any process or methodsteps may be varied or re-sequenced according to alternativeembodiments. In the claims, any means-plus-function clause is intendedto cover the structures described herein as performing the recitedfunction and not only structural equivalents but also equivalentstructures. Other substitutions, modifications, changes and omissionsmay be made in the design, operating conditions and arrangement of theexemplary embodiments without departing from the scope of the presentapplication.

It should be noted that although the figures herein may show a specificorder of method steps, it is understood that the order of these stepsmay differ from what is depicted. Also two or more steps may beperformed concurrently or with partial concurrence. Such variation willdepend on the software and hardware systems chosen and on designerchoice. It is understood that all such variations are within the scopeof the application. Likewise, software implementations could beaccomplished with standard programming techniques with rule based logicand other logic to accomplish the various connection steps, processingsteps, comparison steps and decision steps.

The invention claimed is:
 1. A magnetic self-aligning coupling devicefor a fiber optic cable comprising: a first end coupling comprising afirst magnet; the first magnet comprising a first mating surface, afirst diameter and a first annular ring defining an axial firstaperture; the first aperture for receiving a first distal end of a firstsegment of fiber optic cable; the fiber optic cable comprising anexterior sleeve and a fiber core; the first magnet disposed in an firstannular space in a first module, the annular space greater in diameterthan the first diameter that allows the first magnet to move within thefirst annular space; a second end coupling comprising a second magnet;the second magnet comprising a second mating surface; a second diameterand a second annular ring defining an axial second aperture; the secondaperture for receiving a second distal end of a second segment of fiberoptic cable extending into the second aperture; the fiber optic cablecomprising an exterior sleeve and a fiber core; the second magnetdisposed in a second annular space in a second module, the secondannular space greater in diameter than the second diameter that allowsthe second magnet to move within the second annular space; and whereinthe fiber core of the first segment and the second segment of the fiberoptic cable are axially aligned in the first and second apertures whenmated to create a continuous fiber optic path; and wherein the first andsecond mating surfaces are slidably unmated in direction perpendicularto the axis of the first and second segments of fiber optic cable; andwherein the first and second modules are disposed in first and secondstructures, respectively; and wherein the first structure is a fixedstructure that is not movable relative to the second structure.
 2. Thedevice of claim 1, wherein the alignment of the first segment and thesecond segment is sufficient to transmit an optical signal along thefiber optic path.
 3. The device of claim 1, wherein the first magnetcomprises an outer periphery different from a periphery of the secondmagnet, and wherein each respective magnet is symmetrical axially. 4.The device of claim 1, wherein the first magnet has an aperture radiusdifferent from an aperture radius of the second magnet, and wherein eachrespective magnet is symmetrical axially.
 5. The device of claim 1,wherein the first magnet and the second magnet comprise one ofneodymium, rare-earth magnet or permanent magnet material.
 6. The deviceof claim 1, wherein the fiber core comprises a plastic core.
 7. Thedevice of claim 1, wherein the first magnet and the second magnet havingopposing magnetic polarities; and wherein the first magnet and thesecond magnet are joined by magnetic attraction at the respective firstmating surface and second mating surface.
 8. The device of claim 1,wherein at least one of the first magnet and the second magnet arecomprised of neodymium.
 9. The device of claim 1, wherein the firstmagnet and the second magnet are comprised of rare-earth magnets. 10.The device of claim 1, wherein the first magnet and the second magnetare permanent magnets.